IUCr Congress

XXIV IUCr Congress: Microsymposium reports

Instrumentation techniques and/or Computation

MS-006: Computational materials design

Chairs: Samrath Lal Chaplot and Artem R. Oganov

The microsymposium had six excellent presentations that spanned a broad range of computational studies and addressed important issues such as the topological structures, dynamics, algorithms, machine learning, predictions and classification of important features. Eugeny Alexandrov talked about multilevel topological analysis and creation of a knowledge database that could be useful in the design of coordination networks. Matthew Dunstan explained methods of effective screening of databases of crystal structures to design materials especially for carbon capture and storage, and oxygen ionic conductivity. Sandro Scandolo talked about high-pressure studies of SiO2, highlighting the atomistic pathways in transitions to metastable crystalline and amorphous structures. Jonathan Skelton made a lucid presentation on the role of lattice dynamics in materials modelling and design. Ivan Kruglov explained machine-learning algorithms to derive interatomic potentials and used it in the evolutionary algorithm USPEX to investigate the phase diagram of uranium. John Rodgers talked about extensive use of databases and computation including machine-learning methods in materials design and discovery. Overall, it was indeed interesting to listen through various talks that brought out how the microscopic understanding of structure and dynamics is now applied to predictions of new materials with desired properties that could be tested by experiment.

MS-013: Quantitative electron imaging and tomography

Chairs: Andreas Rosenauer and Eric Van Cappellen

This microsymposium focused on exciting new developments in the field of quantitative transmission electron microscopy. The first two invited talks presented by Ivan Lazic and Knut Müller-Caspary demonstrated measurement of the momentum transfer from which the electrostatic specimen potential, atomic electric field and charge density can be obtained with sub-ångström spatial resolution. The first technique uses a segmented detector, the second a pixelated detector. A third approach to measure the phase of the object function and thus the specimen potential was shown by Peter Nellist, who demonstrated detection of charge transfer from the B to the N site in hBN. The third invited talk presented by Georg Haberfehlner shed light on the state of the art in electron tomography, demonstrating 3D reconstruction of atomic structure and of composition with spectroscopic techniques. First experiments towards 3D measurement of strain with electron tomography were shown in the talk by Duncan N. Johnstone.

MS-024: NMR crystallography and related methods

Chair: Manish Mehta

This microsymposium, featuring six leading practitioners in the emerging field of NMR crystallography, was held on the Wednesday morning of the Congress. It came on the heels of a successful keynote lecture by David Bryce on the Tuesday evening titled, “Structure and Properties of Materials by Solid-State Nuclear Magnetic Resonance Observables.” (That keynote had over 60 members in the audience.) Both the keynote and the microsymposium were the first of their kind at an IUCr Congress. At its peak, the microsymposium had nearly 60 members in the audience. NMR crystallography, while an emerging discipline, is broad in its scope, ranging from technique development to applications in a variety of areas. The six presentations reflected this breadth in an impressive way, and those who stayed for the full session came away with an appreciation of the scope of the field as well as its direction. The talks were not too technical - which they could easily have been - and were broadly accessible to the audience. On a procedural matter, all speakers kept their talks within the advertised time limits, and they stuck to the advertised talk titles. The presentations were of a complementary nature and gave a good feel for the questions that are being addressed and the tools employed to tackle those questions. P.K. Madhu gave an excellent overview of cutting-edge NMR capabilities and their potential application to crystallography, while Yusuke Nishiyama showed what can be accomplished with proton chemical shift tensors. Sachin Chaudhari, who has just completed a postdoc with Lyndon Emsley in Lyon, spoke about the utility of dynamic nuclear polarization, while James Harper spoke about the possibility of determining crystal structures using NMR data alone. Gerd Buntkowski and Jurgen Senker spoke about powerful applications of NMR crystallography in the study of enzymes and polymer additives, respectively. In all, this was a highly successful microsymposium, which made a valuable addition to the overall scientific programme.

MS-050: Small angle scattering studies of biomacromolecular kinetics

Chairs: Pau Bernado and Clement Blanchet

This microsymposium assembled presentations that reflect the present progress of SAXS, which has become an essential tool to structurally characterize biomolecules in solution. The novel experimental setups presented allow the monitoring of complex biological phenomena or the recording of new observables to structurally probe biomolecules. Two speakers presented the current developments on their beamlines. Automated sample collection and chromatography coupled with SAXS available on the BM29 beamline (ESRF, Grenoble) were presented, together with the plans for the future upgrade at the ESRF. The presentation of the P12 beamline (EMBL/PETRAIII, Hamburg) focused on the opportunities in anomalous SAXS and time-resolved experiments. The high-flux option at the P12 beamline, allowing the collection of data at the sub-ms time scale, is particularly interesting for time-resolved studies of biomacromolecular kinetics. Two presentations focused on the application of SAXS for the study of complex biological phenomena covering multi-component equilibria in biological systems and in crystallisation processes. Interestingly, both studies were made possible through the development of microfluidic sample environments, which have a growing impact on modern synchrotron SAXS beamlines. The new data collected on these setups will foster the development of theoretical approaches for their interpretation from a structural perspective.

MS-059: Quantitative electron diffraction

Chairs: Mauro Gemmi and Enrico Mugnaioli

This microsymposium has confirmed the growing interest in electron crystallography, attested by the remarkable number of participants. The broad range of methods and applications presented by lecturers displayed that this field is in continuous and fast expansion. Results from the first in situ electron diffraction tomography (EDT) experiment on a Li-containing nanodevice during a charge cycle were shown, which allowed an estimation of the variation of the Li occupancy at different crystallographic sites. The recently developed dynamical refinement method has been extended to modulated crystal structures with the introduction of new criteria for reflection assignment and sorting. Electron diffraction tomography may now also be applied to protein nanocrystals. Novel results show that energy-filtered EDT data allowed not only the solution of the protein structure with atomic resolution, but also the detection of its charged states. The expansion of electron crystallography into all the classical fields of crystallography is endorsing electron crystallography as the eligible technique for any structural problem at the nanoscale.

MS-068: New X-ray sources: storage rings, FELs and laser-based

Chairs: Tetsuya Ishikawa and Harald Reichert

Over the past two decades, we have seen great strides in the advancement of X-ray source technology with about 50 facilities operational worldwide today. Now we are facing the transition of storage-ring technology from double-bend-achromat (DBA) to multi-bend-achromat (MBA) lattices for smaller horizontal electron-beam emittance. At the same time, X-ray free-electron lasing (XFEL) has been achieved using self-amplified spontaneous emission (SASE) technology. In 2005, the FEL, FLASH at DESY, Germany, started operation in the soft X-ray range, followed in 2009 by the first XFEL in the hard X-ray range at the LCLS in Stanford, California, USA, and in 2011 by SACLA at Harima, Japan. This year brought three new XFEL facilities on the stage in Germany, Switzerland and South Korea. In addition, several new types of laser-based X-ray sources are currently under development. The microsymposium was organized by Harald Reichert (ESRF) and Tetsuya Ishikawa (SPring-8/SACLA). It featured three invited speakers providing a review of developments in synchrotron radiation sources, XFEL sources and laser-based sources. In addition, four contributing speakers addressed the following topics: (i) the first MBA machine, MAX-IV, at Lund; (ii) the newly emerging European XFEL; (iii) recent progress in lab-based sources; and (iv) the Kurchatov synchrotron radiation source, which until recently was not widely known. Joel D. Brock of Cornell U., who serves as the director of Cornell High Energy Synchrotron Source (CHESS), gave an overview of existing storage-ring sources as well as planned upgrades and future facilities. He discussed the general scientific implications of the transition to MBA-based technology. Robert Feidenhans’l, the Chairman of the Management Board of the European XFEL GmbH, changed his topic from an overview of SASE-based XFELs to a status update on the European XFEL, because it recently succeeded in lasing and is nearly ready to start user operations. Tetsuya Kawachi of the National Institute for Quantum and Radiological Science and Technology in Japan discussed laser-based X-ray sources through both higher harmonic generation (HHG) and plasma emission. For the first contributing presentation, Marjolein Thunnissen reported on structural biology at MAX-IV, the world’s first operational MBA-based storage ring. She not only discussed structural biology, but also shared the latest results from her facility. Next, Alexander Blagov presented an overview of future imaging and diffraction research at the European XFEL. Although some parts of his presentation overlapped with Professor Feidenhans’l’s talk, Dr Blagov provided interesting details on the introduction of Russian contributions to the European XFEL. Vernon Smith of the Bruker Corporation gave the third contributing presentation on the topic of laboratory X-ray sources. He reviewed several recent developments achieved by the Bruker Corporation, including a macromolecular crystal structure analysis system. The last talk was given by Roman Senin of the Kurchatov Institute in Russia. He provided an introduction to the Kurchatov synchrotron radiation facility, which has generally not been accessible to scientists outside of Russia. Despite the concurrent topics on crystallography, many audiences participated in this microsymposium. In fact, some of the talks drew standing-room-only participants. In the future, additional consideration should be paid to the size of the meeting rooms and the number of chairs available.

MS-076: Diffuse scattering in crystalline structures

Chairs: Ray Withers and Bernardo Barbiellini

This session was very well attended throughout. It opened with a highly entertaining and informative talk from Andrew Goodwin using tiling to show how even strict local rules need not lead to long-range periodicity. The widespread class of highly correlated disordered materials (including ices, spin glasses, ferroelectrics) and their consequences for physical properties were highlighted and well illustrated. Marek Pasciak then beautifully illustrated the use of large multi-scale molecular dynamics simulations of detailed experimental diffuse scattering data to reliably extract time and space resolved polar fluctuations from four separate ferroic and piezoelectric materials systems. The obtained fits to the observed diffuse scattering data were most impressive. Thomas Weber presented a detailed analysis of the diffuse scattering data characteristic of PbTe, a leading thermoelectric material. This analysis was based on state-of-the art software developed at ETH Zurich for robustly simulating 3D pair correlation distributions. Arkady Simonov illustrated some exciting examples of diffuse scattering spectra where the phase problem could be solved. He also pointed out the existence of a planar extinction condition in reciprocal space and even determined a space-group symmetry for an experimental diffuse distribution. This work opens new opportunities to phase and thereby extract faithful reconstructions in real space from diffuse scattering data. Patrick Tung presented detailed diffuse scattering data of piezoelectric NBT-BT materials under applied electric fields from experiments performed at the ESRF. Big box Monte Carlo simulations were used in order to analyze the experimental data in term of ordered disorder. Ella Schmidt presented an ingenious fitting method for studying diffuse scattering. The method introduced molecular form factors and thus dramatically reduced the computational effort required with respect to standard brute force Monte Carlo simulations.

MS-077: Coherence, spectroscopy and time resolved crystallography with new sources

Chair: Jan Kern

The microsymposium covered a large range of techniques as well as samples studied, illustrating the wide application of time-resolved X-ray techniques using new experimental approaches. These ranged from X-ray spectroscopy with tens of fs time resolution at SACLA (Katayama, SACLA) through elucidation of details of protein-cofactor interactions in time-resolved fs crystallography (Standfuss, Paul-Scherrer Institute), the progression of electric potential induced density waves in alloys studied in the hundreds of fs time range using slicing techniques at synchrotron sources (Ravy, University of Paris) to slower time-resolved diffraction experiments in the microsecond timescale conducted on organic molecules at home sources (Basuroy, SUNY Buffalo). A common theme in most of the talks was the important role of new enabling technology to perform these demanding experiments, for example advanced beam analytics at SACLA to reduce the timing jitter in ultrafast time-resolved experiments (Katayama), the transfer of sample-delivery methods developed for XFEL experiments into synchrotron experiments (Standfuss) or the development of novel ultrafast read-out detectors like the EIGER (presented by Brandstetter, Dectris Ltd). The audience covered a wide range of expertise (materials science, physics, X-ray spectroscopy, structural biology), making for a lively discussion following each of the presentations.

Chairs: F. Damay and M. Henriques

Despite the difficulties encountered during its organisation (mainly because of the lack of submitted abstracts), this microsymposium, although not quite dedicated to technical methods as advertised in its title, was a very stimulating and successful one. The five speakers gave very good quality talks, and gave very interesting examples of alternative techniques [such as Mössbauer spectroscopy, to identify S=0 spins (Ling)] to solve magnetic structures when neutron scattering gives equally likely possible solutions. A variety of different materials, ranging from magnetoelectrics to thermoelectrics, were presented, broadening the interest of the audience. The invited speaker, Stephen Collins from Diamond (UK), gave a particularly interesting talk on the specifics of resonant and non-resonant X-ray scattering techniques, applied to investigate the subtleties of magnetic structures (like very small spin canting), which cannot be fully apprehended by neutron diffraction. His presentation on the possibility of using Compton scattering - an inelastic X-ray scattering process that yields a projection of the electron momentum density - to probe magnetoelectrical properties, could have a lot of impact on this field in the nearby future to identify unambiguously time reversal or space inversion in crystal structures. Overall the session was well attended, and a good synergy between the attendees and the speakers was noticed.

Chairs: Regine Herbst-Irmer and Jacob Overgaard

In this microsymposium six speakers presented experimental charge-density investigations into inorganic materials, organic small molecules and proteins using powder or single-crystal data collected either in the lab or at synchrotrons. Mads Jørgensen (Aarhus University, Denmark) described the investigation on powder with the new ‘Aarhus Vacuum Imaging Plate Diffractometer’. Then Nicolas Claiser (Université de Lorraine, France) compared two single-crystal data sets of YTiO3 collected at Bruker (Karlsruhe) and at SPring-8. Parthapratim Munshi (Shiv Nadar University, Tehsil Dadri, India) presented a review of charge-density studies in small molecules and proteins and reported on the new developments in detector technology. Krzysztof Wozniak (University of Warsaw, Poland) talked about precision and accuracy of single-crystal X-ray results, comparing the Independent Atom Model, the Multipole Model, Hirshfeld Atom Refinement and the Transferable Aspherical Atom Model of electron density. Eiji Nishibori (University of Tsukuba, Japan) described the charge-density investigations of LaB6 and BaB6 using powder data collected at SPring-8. Finally, Hidetaka Kasai (University of Tsukuba, Japan) spoke about a charge-density study of TiS2 using single-crystal data collected at SPring-8.

Materials and minerals

MS-070: Superconducting materials

Chairs: Irina Makarova and Rob McQueeney

The discovery of a new class of high-temperature Fe-based superconductors has attracted substantial attention in the scientific community due to providing a new platform for investigations of superconductivity as a phenomenon. MS-070 was dedicated to the crystallography of these superconducting materials, their properties and different aspects of formation. E. V. Antipov (Russia) demonstrated the possibility of the increase of the superconducting transition temperature in Fe1+δSe by more than 30 K by the modification of the crystal structure. Such modification could be performed by the intercalation of Li, Fe or alkaline cations like K in the interlayer space. The data obtained in that study revealed a remarkable new opportunity for Tc-enhancement. A. L. Vasiliev (Russia) introduced the study of low-temperature Nb3Sn based superconductors used for the manufacture of magnetic coils for ITER and LHC projects by means of electron microscopy, including transmission/scanning electron microscopy, nano-electron diffraction and microanalysis, and new data on the microstructure of Gd-Ba-Cu-O layers doped with Sn and Zr in order to obtain pinning centers and on the structure of iron chalcogenide single crystals and thin films including three-dimensional reconstructions. S. Nandi (India) reported data on Eu-based Fe pnictides obtained by X-ray resonant magnetic scattering, and polarized and unpolarized neutron diffraction. The advantages of these experimental techniques for smart materials research were also noticeably shown. The highly sensitive EXAFS for obtaining precise structural data was discussed by S. M. Heald (USA).

MS-097: Functional magnetic materials

Chairs: D. Shoemaker and J. A. Alonso

In this microsymposium, the speakers covered different, complementary aspects of the topic “functional magnetic materials”. J. Cumby (UK) presented an ellipsoidal method for quantifying octahedral distortions in ionic compounds and applied this analysis to magnetite below its Verwey transition. The distribution of ellipses affords a view of the correlations between distortions of neighboring octahedra in “trimerons” in the structure. Applying this method to data-mined sets of Fe3+-O compounds revealed a tendency for the cation to off-center, likely due to second-order Jahn-Teller effects from their 3d5 electron configurations. J. Garcia-Muñoz (Spain) and H. Kobayashi (Japan) presented complex magnetoelectric interactions in cobaltates and EuNiO3, respectively. B. Kennedy (Australia) discussed the interplay of ionic size and spin-orbit coupling in ordered double perovskites containing Ru, Ir and Os. S. Peter (India) introduced novel structures of rare-earth-containing intermetallics and their magnetic properties and transport.

Physical and/or fundamental

MS-017: Extending the boundaries of crystallography

Chairs: Manuel Loquias and Mois I. Aroyo

The microsymposium dealt with recent novel advances in both theoretical and experimental aspects of crystallography. Walter Steurer of ETH Zurich opened the session by giving a talk on the state of the art of research in the structure, formation and growth of quasicrystals and, in particular, of intermetallic quasicrystals. In addition, he gave his perspectives on the immediate goals and challenges in quasicrystal research. The next talk, by Stephen Timothy Hyde of the Australian National University, was on the taxonomy of hyperbolic orbifolds and its application to triply periodic minimal surfaces. The last invited talk, by Tomonari Dotera of Kindai University, Japan, supplemented the previous talks: he discussed self-similar tilings and quasicrystals associated to the bronze mean, and their results on crystal structures on triply periodic minimal surfaces obtained via Monte Carlo simulations of hard spheres. There were three contributed talks to the microsymposium. Alistair Overy presented models to study the relationship between disordered entanglements and swelling in fibrous materials. The talk by Espen Drath Boejesen described how scanning electron nanodiffraction (END) may be used to distinguish between seemingly similar amorphous materials. Finally, Lorraine Andrade Malaspina reported on efforts to map the trajectory of proton transfer in different hydrogen maleate salts with varying symmetry of hydrogen bonds.

This microsymposium induced great interest among the participants of the Congress. Among the speakers were outstanding scientists Gervais Chapuis (Switzerland), Sergey V. Krivovichev (Russia), Branton Campbell (USA), Dhananjai Pandey (India), Stefan Adams (Singapore) and Swastik Mondal (India). In his presentation, Gervais Chapuis considered the superspace concept in applications to crystal chemistry of structural families and polytypes. Sergey V. Krivovichev outlined the original concept of information-based measures of structural complexity of crystals, and discussed the evolution of various natural and synthetic phase systems in this respect. Branton Campbell presented an algebraic approach to identification of rotational rigid-unit modes wherein the conditions of connectedness are used to construct a linear system of equations in the rotational symmetry mode amplitudes. Dhananjai Pandey presented unambiguous evidence for an iso-symmetric phase transition involving coupled order parameters in CaTiO3. Stefan Adams discussed his approach to determine bond-softness adapted bond-valence parameters based on a description of bond valence as a function of valence electron density. Swastik Mondal spoke about a new insight into the bonding mechanism of boron carbide that helps to explain why boron carbide and related materials can preserve the same crystal structure over a range of compositions.

MS-098: Recent advances in quasicrystal research

Chairs: Katariina Pussi and Yasushi Ishii

In the session six talks were given, out of which two were invited and four contributed. The session gave a nice overview of the field including talks on both theoretical aspects and experimental studies. In the first invited talk, theoretical tiling models and a new inflation rule for generating canonical cell tilings were discussed by Nobuhida Fudita (Sendai, Japan). The second invited talk, given by Julia Dshemuchadse (University of Michigan, USA), also presented theoretical aspects, including crystal structures in soft matter and new structure types built by packing polyhedra. One of the contributed talks explicitly brought up the universal question of “from structure to the physical properties – how far can we go?”. This nicely summarizes one of the main targets of quasicrystal research, which was visible in all of the talks in this microsymposium. Subjects covered in other contributed talks included quasiperiodically arranged molecular thin films, icosahedral quasicrystals with rare earth atoms and γ-brass related complex phases in Rh-Cd binary systems.

Chairs: Cy Jeffries and Manfred Roessle

The microsymposium encompassed a number of topics relevant to the standardization practices in the field of small-angle scattering (SAS), with a particular emphasis on biological solution scattering. Alexey Kikhney (EMBL) presented the Small-Angle Scattering Biological Data Bank (SASBDB; sasbdb.org), the largest publicly accessible repository of bioSAS data and models, which included recent SASBDB-PDB developments (integration of SAS into the PDB OneDep system) and new visualisation tools for data quality assessment (‘sliders’). The sliders drew lively discussions from the audience. Brinda Vallat (Rutgers/PDB) detailed the complexities of capturing experimental results and metadata derived from hybrid methods using the CIF file format (dictionaries/ontology). An alternative, fully adaptable system, NXcanSAS (cansas.org), was presented by Pete Jemian (ANL). Combined, these talks highlighted the immense challenges facing the curators of databases where both SAS and hybrid methods are deposited in parallel. Andrew Allen (NIST) gave a rigorous (and important) talk on the development of an internationally recognised glassy-carbon standard for the absolute scaling of scattering intensities. The MS was concluded by Mitchell Guss (USyd) who outlined recommendations for publishing bioSAS data and models described by Trewhella et al. that were published during the IUCr2017 Congress [Acta Cryst. D73, 710-728 (2017)].

Special activities

MS-021: Terminology issues in crystal engineering

Chairs: Carol Brock and Christer Aakeröy

Prior to IUCr2017, the chairs of this session were more than a little apprehensive; would anyone show up for a 2.5-hour symposium dedicated exclusively to terminology issues in crystal engineering? The answer was a resounding ‘Yes!”, as the 250-seat lecture hall was nearly filled for each of the five talks. The session also managed to live up to the billing (as stated in the IUCr Newsletter) of providing a "...popular, lively and indeed humorous session“. Desiraju and Metrangolo delivered detailed insight into how the IUPAC definitions of the hydrogen bond and the halogen bond, respectively, have been arrived at. The time and effort that go into developing appropriate nomenclature that is acceptable by the community are clearly considerable. MacGillivray examined some practical and legal pitfalls that can arise as a result of polymorphism, and terminology resides at the core of many of those issues. Vittal gave an entertaining overview of the frequently entangled descriptions that surround coordination polymers and/or metal-organic frameworks (covering acronyms from MOFs to ZIFs via PIZOFs). Finally, Aakeröy illustrated, with a series of often amusing examples, some of the challenges in deciding exactly what types of solids should be called co-crystals.

MS-032: Crystallography courses around the world

Chairs: Annalisa Guerri and Juan Manuel García-Ruiz

Within a room overcrowded with a participative audience, MS-032 hosted 16 excellent presentations (half of them as posters) on the efforts of our community in teaching crystallography. Several lectures reported the initiatives of the IUCr Regional Associates, including LACA (Diego Lamas), ACA (Amy Sarjeant) and ECA (Alessia Bacchi), along with a report about crystallographic courses in Africa by Andreas Roodt. We heard several presentations on specific Schools, such as the European Master of Crystallography, a one-year master involving different countries in Europe (Fermín Otálora); the FEBS crystallization courses running since 2004 in the Czech Republic (Ivana Smatanova); and the International Schools of Crystallization of Granada, Spain, since 2006 (Jaime Gomez-Morales). Michele Zema reported about the OpenLab courses from North Africa to the Far East and South America, a project born in 2014 for the IYCr and still expanding. Dubravka Jung covered the connection between teaching and industry. Courses on materials physics (Peter Moeck), symmetry (Massimo Nespolo), macromolecular structures (Rusian Sanishvili) and for undergraduate students (Cora Lind-Kovacs) were also reported. The programme was completed with discussions about the IUCr crystal growing competition (Luc Van Meervelt), the Instituto Rocasolano website (Juan A. Hermoso) and educational initiatives in Croatia (Aleksandar Visnjevac).

MS-044: Structural databases as teaching tools - Part A (macromolecules)

Chairs: Joel Sussman and Christine Zardecki

Free public access to structural data and related bioinformatics resources enables a wide variety of educational resources as presented in MS-044. Jaime Prilusky (Israel) demonstrated how simple Proteopedia webpages enlighten macromolecular structure-function relationships for students and researchers. More than 130,000 PDB entries, as well as thousands of user-added pages, can be explored by clicking on text to highlight the corresponding feature in 3D, e.g. a tutorial “How do we get the oxygen we breathe” designed for high school and beginning college students. Shuchismita Dutta (USA) described how looking at disease through a structural biology perspective promotes development of RCSB PDB resources aimed at high school and undergraduate students. In bioinformatics studies, Masters students have used PDB virus structures for analysis and compiled them into specialized prediction databases, leading to an in silico pipeline for vaccine development under the direction of Urmila Kulkarni-Kale (India). At Protein Data Bank in Europe, Sameer Velankar (UK) and his team have used everything from art to topology map depictions as a way of bringing structure to biology and beyond. Alexey Kikhney (Germany) demonstrated how the SASBDB and DARA resources are extremely useful biological solution scattering teaching tools, as well as for getting an initial idea of the overall structure of an unknown protein or protein complex. In the final presentation, Hirofumi Suzuki (Japan) wore red-cyan glasses while demonstrating how playing with 3D biomolecular structures is easy and fun using PC, mobile and VR software tools hosted by Protein Data Bank in Japan.

Chairs: Anthony Linden and Wladek Minor

Five speakers presented different aspects of data validation and data archiving. We have come a long way from publishing printed copies of structure factor tables within journal articles to the full electronic deposition of diffraction data and even diffraction images, because this not only allows the validation of results, but is a full archive that permits interested persons to extract information not thought about or even possible at the time of the original work. Ton Spek (The Netherlands) summed up the aim of validation clearly: results are valid if all data are included and the authors document what was done during the experiment and the thinking behind the decisions made. Loes Kroon-Batenburg (The Netherlands) indicated that the archiving of frame data needs not only public data depositories to cope with the quantity of data, but also the deposition of full metadata, without which it is difficult to reprocess data. Jim Simpson (New Zealand) recounted the discovery of fraudulent crystal structures and how validation tests were expanded to reveal such manipulations. DFT-D calculations can now be used to check the validity of structures determined from XRPD (Jacco van de Streek, Germany). Common issues are poor refinement but structure correct, H-atom errors and element swap errors, as well as the importance of the consideration of preferred orientation. Finally, John Westbrook (USA) described the wwPDB OneDep Validation procedure during deposition of macromolecular structures.

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